If you are measuring a car speaker, you will need to remove any panels and screws that get in the way of the speaker. The way you do this will be different from one car model to the next. Consult your user’s manual for instructions. If you are measuring home speakers, unscrew or slide the covers off the speaker cabinets.
Some car speakers may be placed in a speaker harness. This is a large metal box that the speaker sits in. If so, you can also detach the wire to the harness and remove the harness. [2] X Research source
If the mounting hole is a shape other than round, measure the widest point on all sides.
If the speaker isn’t round, find the widest point on each side if you have a speaker hole that isn’t round.
If you get a speaker that’s too tall for your speaker cabinet or panel, you could damage the speaker or it won’t sit flush when you mount it. The back of the speaker should not make contact with the back of the speaker cabinet or car panel.
You can also trace the pattern of the screws on a sheet of paper so you have a visual comparison while you’re shopping for speakers. Speakers will come with the mounting screws needed to secure them in place. If you can’t find speakers that have the same screw pattern, you may have to drill your own holes.
If you have a speaker that isn’t round, measure the widest points of each side so know all the dimension. If there are any flat edges, measure from one flat edge to the other.
If your speaker isn’t round, measure the widest point from each side so know each dimension. The cutout diameter needs to be the same size or slightly smaller than the hole where you plan on installing the speaker.
If you have a speaker that’s too tall for the area where you’re putting it, then it won’t sit flush, or it may get damaged when you try to insert it. Be sure to get a new speaker that will not make contact with the back of the speaker cabinet or panel.
The height that extends out from the mounting plate is important since one that extends too far could get damaged and bump into things. For example, if you have a car speaker that’s too tall, it could damage the cone if you close your car door.
Impedance is measured in Ohms (Ω). If you are measuring a car speaker, consider the power rating of your stereo system. If you have a high-power system, you will want to go with a low-sensitivity speaker. If you have a low-power stereo system, you will want to go with a speaker that has a higher sensitivity.
